Review of cumulative effects management concepts and international frameworks

Jackie Lerner

UBC Institute for Resources, Environment, and Sustainability
Aquatic Ecosystems Research Laboratory
429-2202 Main Mall
Vancouver, BC Canada V6T 1Z4

January 2018

Prepared for Transport Canada under Contract T8080-170062

Executive summary


Transport Canada wishes to familiarize itself with current conceptions and implementations of regional cumulative effects management frameworks— systems of policies, procedures, and tools that enable management of cumulative effects at a broader regional scale— particularly as they relate to marine shipping activities, with the goal of ultimately developing a Canadian framework to be implemented at the regional level. This report has been prepared to address that objective. Transport Canada’s specific issues of interest included (1) guidance on selecting temporal and spatial scales, (2) identifying valued components, and (3) applied examples from international practice.

The author conducted a literature review of international cumulative effects management frameworks with a focus on marine shipping and coastal contexts. Sources for the review were identified from a search of academic and grey literature and from the author’s professional experience, as well as on the recommendation of Transport Canada, Fisheries and Oceans Canada, and knowledgeable colleagues.


Common themes drawn from the literature included (1) cumulative effects management terminology and concepts, (2) common tools and models, and (3) best practices and challenges—whenever possible, with a focus on marine and coastal contexts. Highlights of this synthesis are provided in the following paragraphs.

Much recent literature broadly conceptualizes approaches to assessing and managing cumulative effects as:

  1. project-level approaches, where emphasis is placed on the cumulative impacts of individual and multiple development projects by essentially expanding environmental impact assessment methods over larger spatial and temporal scales; and
  2. strategic approaches, where emphasis is placed on the cumulative effects of proposed or existing plans or development initiatives in a formal and systematic way that allows decision-makers to take cultural, economic, environmental, and social considerations into account early in the planning process.

While the precise terminology varies, cumulative effects management frameworks generally consider the relationships between six key elements. Depending on what a cumulative effects management framework is designed to achieve, one of these key elements becomes the framework’s starting point or focus:

  • valued components: specific parts of the human, biotic, or physical environment considered important because of their cultural, social, aesthetic, economic or scientific value, such as water quality or beluga whales;
  • activities: things that humans do, such as building ports, fishing, or marine transportation;
  • sources: specific aspects of or actions associated with activities—such as pile driving for port construction—with the potential to generate environmental pressure;
  • stressors: environmental pressure, such as sedimentation and noise;
  • pathways: mechanisms or causal links, such as exposure to water with high concentrations of sediment, by which stressors act on valued components; and
  • effects: changes to valued components as the result of stressors, such as lowered water quality or decreased biodiversity.

For Transport Canada’s purposes, a strategic, activity-based framework (i.e., one that focuses on the assessment of a single activity or sector) is most appropriate, since the goal is to manage the way that the effects of marine shipping, specifically, act cumulatively on the human and biophysical environment.

Many types of tools and models are used to help identify and organize cause-effect linkages between activities and cumulative effects on valued components. These tools enable managers to prioritize among issues, facilitate communication with decision-makers, and provide a consistent basis for reporting.

  • causal frameworks, such as the Drivers–Pressures–State Change–Impact–Response (or DPSIR) framework, the enhanced DPSIR (or eDPSIR) framework, and Pathways of Effects (PoE) models map links from activities to effects on valued components, and can help identify appropriate control points and management responses.
  • ecological risk assessment frameworks (ERAFs) are used to identify activities that pose the greatest risk to valued components, often scoring risk along two axes: (1) the exposure of a population to a human activity, and (2) the sensitivity of or consequences to the population for that activity, given a particular level of exposure.
  • ecosystem models allow for computer-aided simulation and visualization of complex relationships within marine ecosystems. Two highly regarded marine ecosystem modeling frameworks that deal with cumulative impacts are Ecopath with Ecosim and Atlantis. Both frameworks attempt to model all elements of an ecosystem’s food web, from primary producers to top predators.
  • cumulative impact mapping overlays human activities and associated stressors with maps of habitats, assigning a vulnerability score to different habitat types, and modelling an impact score for each combination of activity-caused stressor and habitat. The resulting map provides an easily understood reference useful for evaluating where conservation and management efforts should be focussed, where development activities should be curtailed or relocated to less vulnerable areas, and where development can continue without serious consequences to the marine environment.

Best practices and challenges identified in the reviewed literature related to (1) selecting valued components, (2) selecting indicators, (3) setting temporal and spatial scales, (4) addressing uncertainty, and (5) public and Indigenous participation.

Selecting valued components focuses the process of assessment and management on ‘what matters’, allowing frameworks to place greater emphasis on components that may require enhanced management or be of particular importance to people or to the ecosystem. The literature offers a variety of methodologies for identifying valued components, typically basing their value to people and their ecological importance on input from Indigenous groups and the public, as well as scientific and professional judgement.

Selecting appropriate indicators involves consideration of important trade-offs. Effects-based indicators measure a characteristic of a valued component (e.g., marine mammal abundance), while stressor-based indicators measure the stress, disturbance, or risk to a valued component (e.g., percent of disturbed marine mammal habitat); essentially, the stressor becomes the indicator. Effects-based indicators are direct measurements of the valued component and inherently encompass cumulative effects of activities, but may not be as useful to decision-making because the cause-effect linkages are poorly understood, and are harder to monitor and generalize. Conversely, stressor-based indicators are usually well understood and can be more simply measured and proactively linked to management actions, but do not capture the effects of all human activities, or the non-additive ways effects from multiple activities can accumulate.

Similarly, the choice of temporal and spatial scales can have profound implications on any study’s results. Narrower scales simplify assessment, but at the risk of neglecting wider-ranging or longer-term effects; on the other hand, larger scales are more appropriate to understanding the broader context of cumulative effects, but may lead to data availability challenges, in addition to effectively diluting the importance of local effects against a too-broad study area. Consideration should be given to a scale that represents both the processes and the actors that influence human activities or are affected by those activities. Whatever scale is ultimately selected, the rationale for the selection should be public and transparent.

Scientific findings are nearly always limited by uncertainty. It is important to explicitly acknowledge these uncertainties and any methodological steps taken to work around them. Application of the precautionary principle and adaptive management are common prescriptions for addressing uncertainty.

  • The precautionary principle is the maxim that, where there is no full scientific certainty about the potential for serious or irreversible damage from a proposed activity, policy decisions should be made in a way that errs on the side of caution with respect to the environment and human well-being.
  • Adaptive management is an iterative approach for improving management in the face of uncertainty by learning from management outcomes and feeding that learning back into the management process.

Participation in impact assessment and management processes has been the focus of much literature over the past two decades. Of particular importance is the participation of Indigenous peoples, especially those who elect to maintain a traditional relationship with their land, and for whom assessment and management decisions will have serious implications. In addition, in Canada, Indigenous peoples have constitutionally recognized rights and title and treaty rights with direct relevance to environmental decisions. As one writer argues, the goal of this participation should be to improve quality, legitimacy, and capacity, where:

  • quality refers to identification of the values, interests, and concerns of all who are interested in or might be affected by the assessment or decision together with the range of actions that might be taken; consideration of the effects that might follow and uncertainties about them; application of the best available knowledge and methods relevant to the above tasks; and incorporation of new information, methods, and concerns that arise over time;
  • legitimacy refers to a process that is seen as fair and competent by the interested parties and that follows the governing laws and regulations; and
  • capacity refers to the benefits to all participants of gaining knowledge and skills, both by becoming more informed about the intricacies and variety of perspectives on the subject of the process, and by gaining experience in the participation process itself.

Realization of these three goals offers benefits for all, particularly decision-makers.

Case studies

Seven case studies of implemented cumulative effects management systems were reviewed: four from international regimes and three from regional initiatives from across Canada:

  • The Barents Sea Integrated Management Plan (Norway);
  • The Great Barrier Reef Strategic Environmental Assessment (Australia);
  • The Xiamen Integrated Coastal Management Plan (China);
  • The Mauri Model Decision-making Framework in post-Rena assessment (New Zealand);
  • The Manitoba Hydro Regional Cumulative Effects Assessment (Canada);
  • The Canada-Nova Scotia Offshore Petroleum Board Strategic Environmental Assessments (Canada); and
  • The Metlakatla Cumulative Effects Management Program (Canada).

Table 1 compares the issues and practices discussed in the synthesis section (above) across all seven of these case studies.


Two broad but valuable principles for developing a cumulative effects management framework became apparent during the course of this review. The first is recognition of the necessity of an iterative and transparent approach to framework development: one that allows for improvements over time as knowledge grows and new opportunities arise. The second principle relates to the importance of navigating trade-offs. If we try to consider too many factors in any analysis, we may render our task impossible. However, by constricting a cumulative effects framework’s scope, we may omit factors that have important bearings on the effects we wish to manage. The key in most cases is finding the right balance between different options.

Table 1. Comparison of case studies reviewed
Name Approach Project / Strategic Tools used Temporal scale Spatial scale Valued component selection Indicators
Barents Sea Integrated Management Plan (Norway) Place-based / Activity-based Strategic Risk assessment and professional judgement Mostly forward-looking (to 2020); historical data on valued components to create pre-development baseline 1,400,000 km2, based on ecological and administrative considerations Method for selection not reported, but seems to have been done by expert group. Effects-based
Great Barrier Reef Strategic Environmental Assessment (Australia) Place-based Strategic DPSIR framework, structured lists, conceptual diagrams, and models Focuses on present to – 2050, but considers older “legacy impacts” 346,000 km2, based on ecological bounds Selected based on scientific significance and value to Traditional Owners Effects-based
Xiamen Integrated Coastal Management Plan (China) Place-based Strategic DPSIR framework Unknown Unknown Professional judgement, with some exceptions Effects-based and stressor-based
Mauri Model Decision-making Framework in post-Rena assessment (New Zealand) Place-based Strategic Decision support 100 years ago to present Not measured in kilometres, but by affected community Participatory Effects-based
Manitoba Hydro Regional Cumulative Effects Assessment (Canada) Activity-based (?) Project Pathways of Effects 1951 – 2013 210,000 km2, follow “ecologically meaningful” boundaries Professional expertise and desk-based (review of traditional knowledge Effects-based
Canada-Nova Scotia Offshore Petroleum Board Strategic Environmental Assessments (Canada) Activity-based Project Professional judgement (?) Present + 10 years 37,280 km2, area, but considers extent of valued components Scientific judgement, board input, and consultation (via the board) Unknown
Metlakatla Cumulative Effects Management Program (Canada) Place-based Strategic Participatory processes Unknown Metlakatla traditional territory Participatory Effects-based

This report proposes a sequence of procedural steps for developing Transport Canada’s cumulative effects management framework, listed below (and more fully defined in Chapter 5).

  • Step 1: Define and document the draft terms of reference;
  • Step 2: Define and document the framework scope;
  • Step 3: Communicate with agencies, partners, and stakeholders;
  • Step 4: Develop a priority set of valued components and indicators;
  • Step 5: Develop an assessment toolkit;
  • Step 6: Develop a management and response toolkit;
  • Step 7: Implement the pilot phase; and
  • Step 8: Evaluate, iterate, and improve.

Within these steps, framework tasks are allocated to three groups within a proposed governance structure: the Steering Committee (providing federal government oversight and overarching departmental control), the Framework Design Group (responsible for preliminary planning and reporting tasks), and the Working Group (with membership from a broad variety of agencies, interest groups, and other stakeholders.